The dual mechanism underlying laser excitation of bulk and surface elastic waves in ablative regime

Abstract

It is usually considered that plasma pressure impulse is the only mechanism corresponding to the laser excitation of bulk and elastic surface waves in an ablative regime. We report the first observation of a dual mechanism where the laser-induced shockwave impacts the target and generates secondary bulk and surface elastic waves some dozens of nanoseconds after the primary ones are generated by the plasma pressure impulse. We propose that the superimposing of the two wave groups can cause additional frequency components that should be considered in research and applications employing elastic waves generated by strong laser ablation.